This invention relates to a novel valve in general and more specifically to a valve construction embodying a novel seal or sealing means. The particular valve assembly here involved and the novel seal which forms a part of the valve assembly are particularly well suited for use in the liquid food dispensing industry but are by no means restricted to such application.
For ease of description, the seal will be referred to hereinafter as a xe2x80x9cseat cup.xe2x80x9d Seat cups, in general, are widely known and derive their name from the fact that they act against a valve seat and have an overall cup-like configuration. Seat cups are generally fabricated from silicone or a like elastomeric resilient material and include a cylindrical base portion and a co-axial nipple portion extending from the base portion and connected thereto by a shoulder. The nipple portion is reduced in cross-sectional dimension with respect to the base portion and is generally cylindrical or frusto-conical converging away from the base. This assembly forms an upwardly opening chamber or recess resembling a cup. The nipple portion terminates in a surface transverse to the longitudinal axis of the seat cup, thereby providing a free or distal end which, as will become apparent hereinafter, provides a portion which is adapted to cooperate sealingly with a valve seat.
When a seat cup of this prior design is operatively placed in the seal chamber of a valve, the base portion is held against axial and lateral displacement relative to the valve body in a position aligned with, but removable from, the valve seat. The nipple portion extends from the base portion toward the valve seat and its free end engages the seat in a fluid-tight sealing relationship to control fluid flow through the valve. A suitable means is employed to mount the nipple removably to the inner end of a reciprocal valve stem which is also aligned with the valve seat. The valve stem projects outwardly from the seat cup recess and an opposite, free end of the stem is connected to an actuator. Upon use of the actuator to move the stem away from the seat, the nipple portion of the seat cup is also partially retracted relative to the seat. Due to flexure at the shoulder, the nipple portion telescopes within the base portion when retracted. Such retraction results in breaking the seal at the valve seat, thereby permitting fluid flow through the valve.
Heretofore, the seat cup has been biased into sealing engagement with the seat through use of a separate spring. In prior devices, a coil spring is coaxially positioned about the stem and a first end of the spring is engaged with a flange on the inner end of the stem while a second end of the spring is engaged with a fixed portion of the valve. The spring ensures that the nipple portion of the seat cup is maintained in tight sealing relation with the valve seat. While this arrangement has proven to be effective, use of a spring adds considerable cost and some complexity to the valve. Therefore, in light of the foregoing, it has been deemed desirable to develop a xe2x80x9cspringlessxe2x80x9d seat cup which includes means integral therewith for positively biasing the seat cup into engagement with the valve seat after being retracted away from same, even after many cycles of use.
In accordance with the present invention, a seat cup seal for a valve includes a base portion and a nipple portion projecting outwardly from the base portion. The nipple portion and said base portion define a blind bore about a longitudinal axis that opens in the base portion. The nipple portion defines a transverse end wall at an outermost end relative to the base that is adapted for sealingly engaging an associated valve seat. A flexible shoulder portion interconnects the base portion and the nipple portion so that said nipple portion is selectively movable between a first, relaxed position where the transverse end wall is spaced a first distance from the base and a second, retracted position where the transverse end wall is spaced a second distance from the base, with the second distance being less than the first distance. A plurality of biasing ribs projects outwardly from and extending between the base portion and the nipple portion. The biasing ribs, which are conformed in one of several suitable arrangements, bias or urge the nipple portion toward the first position when it is in its second position. In this manner, the seat cup does not require a coil spring or other separate biasing agent to urge the transverse end wall into sealing engagement with the associated valve seat.
One advantage of the present invention is that it provides a new and improved seat cup for a valve which does not require use of a separate spring for biasing the seat cup into engagement with a sealing seat of the valve.
Another advantage of the present invention resides in the provision of a springless seat cup which includes smoothly transitioned regions between interconnected portions and controlled wall thicknesses so that it resists breakage even after many thousands of cycles.
A further advantage of the present invention is found in the provision of a springless seat cup for a valve which greatly simplifies assembly of the valve and reduces the cost of same.
Still other benefits and advantages of the present invention will become apparent to those of ordinary skill in the art to which the invention pertains upon reading and understanding the following specification.